*The protiens, carbohydrates, oils, vitamins etc, which are ingested as food nourish the dhatus and provide strength and colour,intelligence, longevity etc. But this is possible only when the ingested external elements are successfully converted into body elements. This entire process is called digestion and metabolism, and the substances that carry out these processes are refered to as agnis. Different enzymes are produced by these agnis in the stomach, liver and dhatu channels to carry out digestion.
*The entire digestive system begins in the mouth. The food mixed with saliva and taste is perceived. Food then moves to the stomach where it turns watery foamy, soft and smooth due to the action of the stomach juice watery foamy,soft and smooth due to the action of the stomach juice which is liquid and oily. Here foamy kapha and sweet rasa are produced.*This half digested food reaches the intestines via duodenum. Here 'samaan vayu' and 'pachak pitta' act upon it, segregate the food into two parts (1) saar (2) Asaar or kitt. If samanavayu and pachak pitta are in now intensity, then the toxins are formed and the ras becomes sour and bitter. These toxins are the cause of disease.*The digested saar used for further nourishment and asaar which is not digested properly becomes the kitt(waste). It's solid part becomes stool, the liquid part becomes urine, and collects in the bowels. The agnis convert the form of five elements in the digested food to match the form fund in the body. This nourishes the earth element formed in the body.This ahaar ras is circulated around the body as the ras dhatu through the srotas - channels. This nourishing ras in which are inherent building blocks of all dhatus, thus reaches all the parts of the body.*The digestive action of the agni - enzymes replenishes dhatus and produced ojas. Pitta plays a vital role in this entire digestive process. So ayurveda does not differentiate between pitta and agni.*Aama